Three-dimensional printer



FIG. 1 is a top, front, right perspective view of a three-dimensional printer showing our design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left-side view thereof;

FIG. 5 is a right-side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines illustrate portions of the three-dimensional printer that form no part of the claimed design. 

CLAIM The ornamental design for a three-dimensional printer, substantially as shown. 